Coating aids for film-forming coating compositions

ABSTRACT

WHEREIN: M stands for hydrogen, an alkali metal atom, ammonium or organic ammonium, N STANDS FOR 0 OR 1, R3 stands for hydrogen or when n 1 may be alkyl, and EACH OF R1 and R2 stands for a straight-chain or branched-chain alkyl group or together represent the atoms necessary to close an alicyclic ring structure, AND THE USE OF THE AFORESAID HYDROPHLIC COLLOIDS IN PHOTOGRAPHIC ELEMENTS ARE DESCRIBED. The coating compositions are excellent inexpensive synthetic coating aids in photographic elements.   D R A W I N G Coating compositions comprising a hydrophilic colloid and at least one surface active compound corresponding to the formula:

United States Patent 1191 Pollet et al.

[111 3,793,032 14 1 Feb. 19, 1974 1 COATING AIDS FOR FILM-FORMINGCOATING COMPOSITIONS [75] Inventors: Robert Joseph Pollet, Vremde;Marcel Cyriel DeFre, Edegem; Arthur Henri DeCat, Mortsel, all of 211Appl. No.: 150,197

[30] Foreign Application Priority Data June 4, 1970 Great Britain...27080/70 52 us. 01. 96/1l4.5, 96/94 R [51] Int. Cl G03! 1/36, G036 H02[58] Field Of Search 96/94, 114.5, 109 R, 94; 106/125 [56] I IReferences Cited UNITED STATES PATENTS 2,719,087 9/1955 Knox 96/114.5

3,026,202 3/1962 Knox 96/114.5

3,068,101 12/1962 Knox 96/114.5

3,415,649 12/1968 NiShlO 106/125 3,525,620 8/1970 NlShiO 96/114.5

2,368,287 1/1945 Chilton 96/109 2,527,260 10/1950 Hart et al 96/1093,516,835 6/1970 Mackay et a]. 96/114.5

OTHER PUBLICATIONS Making and Coating Photographic Emulsions, Zelikman,V.L., 1964, pp. 262-263.

Richter: Textbook of Org. Chem., Third Edition, 1952, pp. 412, JohnWiley.

Rufus A. Lyman, M. D., American Pharmacy, 1945, J. B. Lippincott, pages151-153.

Primary Examiner-J. Travis Brown Assistant Examiner-Alfonso T. Suro PicoAttorney, Agent, or FirmA. W. Breiner [5 7] 1 ABSTRACT Coatingcompositions comprising a hydrophilic colloid and at least one surfaceactive compound corresponding to the formula:

C(CH2)u-SQ3M R2 I ia branched-chain alkyl group or together representthe atoms necessary to close an alicyclic ring structure, and the use(if 1515' aforesaid hydrophhc conoids in photographic elements aredescribed. The coating compositions are excellent inexpensive syntheticcoating aids in photographic elements.

12 Claims, No Drawings This invention relatesto surface-active compoundssuitable for use as coating aids for film-forming coating compositionscomprising a hydrophilic colloid, and to hydrophilic colloidcompositions comprising said coating aids. V a

In the application of film-forming coating compositions comprising ahydrophilic colloid to surfaces, particularly in the photographicindustry, it is desirable to apply such coating compositions uniformlyand at good production speeds. In 'many cases it is even desirable toapply such coatings over other previous layers, which are either wet ordry.

It is necessary, in the photographic industry, that colloid compositionsready 'for coating are entirely hydrophilic to obtain a uniform layertherewith comprising no hydrophobic inclusions that may lead torepellency spots or comets in the said layer. Moreover, the entiresurface of a layer formed from such colloid compositions should behydrophilic so that it can be rewet readily either by the processingsolutions if said layer is the top layer of a photographic material tobe processed, or by the coating compositions that will be applied tosaid layer for forming a next layer. Indeed, during processing,air-bubbles are more easily carried along by a hydrophobic surface thanby a hydrophilic surface, which air-bubbles will manifest themselves assmall undeveloped areas in the processed material; moreover, when thematerial comprises hydrophobic inclusions so that its surface is notentirely hydrophilic but shows hydrophobic areas, water will notuniformly wet the said surface in that it is repelled at the hydrophobicareas and form drops thereomAfter processing such materials cannot bedried uniformly. They show a poor retouchability when it is desired toretouch such-like materials.

In the case wherein the layer formedfrom the said colloid composition isovercoated with a following layer, the maximum speed of the moving layerto be overcoated, at which no repellency occurs can be increased, whenand to the extent that the surface to be overcoated is more hydrophilic;local hydrophobic areas at the surface of the layer to be overcoated cangive rise to the formation of so-called repellency spots or comets inthe said next layer.

Thus, in order to eliminate all these possible coating defects such asair bubbles, repellency spots, or comets the use of coating aids hasbeen widely adopted.

Saponin is conventionally used as coating aid for coating compositionscomprising hydrophilic colloids. Though this product excells by itsfavourable anticomet action, it may vary markedly from batch to batchand is much more expensive than synthetic coating aids. Moreover, it mayadversely affect the photographic properties of an emulsion-containingit.

A number of synthetic surface active agents have been proposed for useas coating aids to facilitate the coating of compositions comprisinghydrophilic colloids more particularly gelatin layers. Most of thesecoating aids do improve some properties of the layer. However, theyadversely affect other desired properties. For instance, hydrophiliccooloid layers comprising coating aids, which prevent the formation ofcomets in the said layers, may have an inadequate rewettability, whichcauses difficulties in the processing of photographic elements or it maybe difficult to werecat such layers when in wet state, which is quiteundesirable especially in simultaneous multilayer applications. In orderto overcome these disadvantages it has been proposed to use mixtures ofcoating aids having different properties.

It has now been found that surface-active compounds corresponding to thefollowing general formula:

wherein: M stands for hydrogen, analkali metal atom such as lithium,sodium and potassium, ammonium or organic ammonium, e.g., diethanolammonium, triethanol ammonium, triethyl ammonium and morpholinium, and Rstands for a branched-chain aliphatic group of 10 to 20 carbon atoms,preferably an aliphatic group of the formula C(CHz)n wherein n is 0 or1, R stands for hydrogen or when n 1 may be alkyl such as methyl andeach of R and R stands for a straight-chain or branched-chain alkylgroup or together represent the atoms necessary to close an alicyclicring structure are excellent inexpensive coating aids for use in coatingcompositions comprising a hydrophilic film-forming colloid such asgelatin.

The coating aids for hydrophilic colloid compositions corresponding tothe above general formula can be prepared very easily as illustratedbelow, by oxidation of the corresponding mercaptans derived fromalicyclic alcohols or branched-chain alcohols.

As an example of an alicyclic alcohol, from which the correspondingmercaptan and a coating aid according to the invention can be preparedhydroabietyl alcohol be mentioned.

Examples of branched-chain alcohols that can be used for the preparationof the mercaptans and coating aids therefrom are branched-chainaliphatic secondary alcohols such as the commercially availableisotetradecyl alcohol i.e., 2-methyl-7 ethyl-4-undecanol and the widelyknown branched-chain primary oxo-alcohols having at least 10 C-atomssuch as isodecyl alcohol, isotridecyl alcohol, isohexadecyl alcohol andisooctadecyl alcohol. Isodecylalcohol is a commercial material preparedfrom C -olefins (tripropylene) by means of the oxo-synthesis (cfr. H.'Rompp Chemie Lexikon Frank-sche Verlag, Stuttgart, W. Germany) and is amixture of primary branched-chain C -alcohols. Isotridecyl alcohol is acommercial material prepared from C -olefms (triisobutylene,tetrapropylene or di(2-methyl-l-pentene) by means of the oxo-reactionand is a mixture of primary branched-chain C alcohols. Isohexadecylalcohol and isooctadecyl alcohol are commercial materials prepared byaldolcondensation of C or C -aldehydes formed by oxosynthesisisohexadecyl alcohol is a mixture of branchedchain primary C -alcoholsmainly consisting of alcohols as represented by the formula wherein Rdimethylbutyl and R" dimethylhexyl, whereas isooctadecyl alcohol is abranched-chain alcohol for which the following formula is given:

Other branched-chain alcohols, from which the coating aids of theinvention can be derived, are the branched-chain alcohols prepared byalkaline condensation using catalytic amounts of alkali such aspotassium hydroxide at temperatures comprised between 200 and 300 (knownas Guerbet-reaction see e.g., Fette-Seifen-Anstrichmittel, 71, no, 3, p.215-218 (1969)) of a branched-chain or straight-chain alcohol with thesame or other branched-chain or straightchain alcohol.

More details regarding the preparation, the composition and propertiesof branched-chain oxo-alcohols, which can be used to form the coatingaids according to the present invention can be found in Fortschr, Chem.Forsch. Bd. 11/1, pages 121-134.

Examples of coating aids suitable for use according to the presentinvention can be represented by the following formulae:

1. 1SOH33C16-SO3N3 The following preparations illustrate how the coaflngaids of the invention can be prepared.-

COMPOUND l a. Isohexadecyl bromide At a temperature of 70 C, hydrogenbromide was introduced into 914 g of isohexadecyl alcohol until thesolution was saturated. Thewater formed was isolated and the oil takenup in ether. The ether layer was washed till neutral, dried' oversodiumsulphate, and concentrated by evaporation. The residue was distilled.

Boiling point: 140C/4 mm.

Yield: 1092 g.

b. Isohexadecyl isothiouronium bromide 305 g of isohexadecyl bromide and76 g of thiourea in 600 ml of ethanol were refluxed for 16 hours. Theclear solution was concentrated by evaporation and the residuerecrystallised from acetonitrile, cooled, filtered, by suction, anddried at 50C.

Yield: 316 g.

c. Isohexadecyl mercaptan To 228 g of isohexadecyl isothiouroniumbromide in 420 ml of water and 420 ml of ethanol under a nitrogenatmosphere, 36 g of sodium hydroxide were added with stirring. Themixture was then refluxed for 2 hours and cooled. The solution wasacidified with 150 ml of 5N sulphuric acid, poured into 900 ml of waterand extracted with 300 ml of methylene chloride. The methylene chloridesolution was isolated, dried over magnesium sulphate and concentrated byevaporation. The residue was distilled.

Boiling point: C/0.'3 mm.

Yield: 150 g. Y 1

d. Sodium isohexadecyl sulphonate 51.6 of isohexadecyl mercaptan wereadded dropwise in 1 hour, at a temperature of 40C, to 140 ml of nitricacid. The mixture was stirred for 1 hour whereupon it was poured intowater. The oil was isolated, washed with water, which had been saturatedwith sodium chloride, and separated again. The oil was then taken up in100 ml of methanol and 100 ml of hot water at 40C and neutralised withsodium hydroxide. The mixture was extracted withmethylene chloride and,the axtract dried over magnesium sulphate, concentrated by evaporationand further dried at 1 10C.

1 Yield: 61 g.

COMPOUND 2 a. lsooctadecyl bromide At a temperature of 80C and withstirring hydrogen bromide was introduced into 1,000 ml of isooctadecylalcohol untilsaturated. The water formed was separated and the oil takenup in ether. The ether layer was washed acid-free, dried over sodiumsulphate and concentrated by evaporation.

The residue was distilled.

Boiling point: l25C/0.5 mm.

Yield: 1010 g.

b. isooctadecyl isothiouronium bromide 333 g of isooctadecylbromide and76 g of thiourea in 600 ml of ethanol were refluxed for 16 hours. Theclear solution was concentrated by evaporation and the residuerecrystallized from acetonitrile, cooled, filtered by suction and driedat 65C.

Yield: 293 g.

Melting point: 150C.

c. isooctadecyl mercaptan To 245 g of isooctadecyl isothiouroniumbromide in 420 ml of water and 420 ml of ethanol under nitrogenatmosphere, 36 g of sodium hydroxide were added with stirring. Themixture was refluxed for 2 hours and cooled.

The solution was acidified with 150 ml of 5 N sul phuric acid, pouredinto 600 ml of water and extracted with 300 ml of methylene chloride.The methylene chloride solution was is6lated, dried over magnesiumsulphate, and concentrated by evaporation. The residue was distilled.

Boiling point: C/l.3 mm.

Yield: 163

d. Sodium isooctadecyl sulphonate 57 g of isooctadecylmercaptan wereadded dropwise in 1 hour, at a temperature of 45C, to ml of nitric acid.The mixture was stirred for another hour and then poured into 300 ml ofwater. The precipitate formed was filtered by suction, taken up in 300ml of water and 300 ml of methanol and neutralised with sodiumhydroxide. The mixture was extracted with methylene chloride and, theextract dried over magnesium sulphate, concentrated by evaporation, andfurther dried at 110C. 0

Yield: 67 g.

Compounds 3 to 6 were prepared in a similar way from the mercaptansderived from hydroabietyl alcohol, isotridecyl alcohol, 2-butyl octanoland isotetradecylalcohol respectively.

The coating aids according to the present invention promote theuniformity of coating and markedly reduce the tendency to formrepellency spots. Coating compositions containing the coating aids ofuse according to the invention can be applied to dry surfaces as well asto wet surfaces and form layers that can be overcoated easily in wet aswell as in dry state, the said layers being either light-sensitivelayers or not. Lightsensitive hydrophilic colloid materials comprisingthese coating aids also show improved wettability by photographicprocessing liquids.

lt may sometimes be advisable to use blends of two or more coating aidsaccording to the present invention. Indeed, it is observed frequencythat one coating aid according to the invention performs best in onerespect e.g., as regards its anticomet properties, whereas another isdefinitely superior in a different effect, e.g., promoting uniformity ofcoating. These blends provide the major effects required and can oftenshow characteristics superior to either coating aid alone. These effectsmay also result with blends of the coating aids of use according to thepresent invention with known coating aids such as saponin and othersynthetic coating aids.

The coating aids of the present invention have also favourableproperties for dispersing or emulsifying substances in hydrophiliccolloid compositions, which as a result of the presence of said coatingaids also show improved coating characteristics. For instance they aresuitable as dispersing agent or emulsifying agent for substances thatare to be incorporated into layers comprising a hydrophilic colloid andthat would give rise to the formation of repellency spots in said layerswhen no compounds according to the inventionwere present.

Although the coating aids according to the present invention are mainlyintended for use in coating compositions comprising gelatin ashydrophilic colloid, they can also be used as coating aid for coatingcompositions comprising other hydrophilic colloid materials or mixturesof them, e.g., hydrophilic natural colloids, modified hydrophilicnatural colloids or synthetic hydrophilic polymers. More particularlythese colloids may be selected of such film-forming natural of modifiednatural hydrophilic colloids as e.g., glue, casein, zein, hydroxyethylcellulose, carboxymethyl cellulose, methyl cellulose, carboxymethylhydroxyethyl cellulose, gum arabic, sodium alginate and hydrophilicderivatives of such colloids. They may also be selected of suchsynthetic hydrophilic polymers as e.g., polyvinyl alcohol, poly-N-vinylpyrrolidone, polyvinyl amine, polyethylene oxide, polystyrene sulphonicacid, polyacrylic acid, and hydrophiliccopolymers and derivatives ofsuch polymers. In this connection reference is made e.g., to UnitedKingdom Pat. Specification 1,139,891 and to French Pat. Specification1,507,874

6 which relate among others to heatand/or pressuresensitive materialscomprising a recording layer mainly consisting of a dispersion ofhydrophobic thermoplastic polymer particles in a hydrophilic colloidbinder.

it has been found that coating aids according to the present inventionimprove the coating characteristics of coating compositions already at aconcentration as low as 0.01 percent by weight relative to the weight ofdry colloid. Larger concentrations, however, can also be used butgenerally the concentration is not higher than 5 percent by weight basedon the weight of dry colloid.

The coating aids according to the invention are particularly suitablefor use in a coating composition comprising gelatin as hydrophiliccolloid, either as an aqueous solution of gelatin or as a photographicemulsion which ordinarily is composed of an aqueous solution of gelatincontaining as the light-sensitive material therein, a silver halide suchas silver bromide, silver chloride, silver iodide, or mixtures thereofor another light-sensitive substance. The emulsion may contain othersubstances such as sensitizing dyes, hardeners, stabilizers,pH-adjusting compounds, colour couplers, antifogging agents, developmentaccelerators, thickening agents, developing agents, softening agents, orthe like. For instance, the coating aids of the invention are useful ingelatin photographic emulsions, not only those, which are non-opticallysensitized, but also in orthochromatic and panchromatic emulsions. Thisalso includes gelatin emulsions intended for colour photography such asthose containing colour forming couplers and fine-grain emulsions of theLippmann-type.

The coating aids of use according to the present invention and theirmixtures with other coating aids are also very useful in various othertypes of coating compositions in which gelatin is an importantconstituent, for example, in gelatin coating compositions to be appliedas antihalation layer to the back or front of the base in a photographicmaterial, as protective layer, as filter layer, as intermediate layer,as anticurling layer, etc. which layers can also contain all kinds ofother ingredients such as filling agents, hardening agents, antistaticagents,'antifriction agents, or in any type of gelatin layer, which iscoated from a composition comprising an aqueous solution of gelatin.

The coating compositions in'accordance with our invention may be coatedon a transparent support. e.g., of glass, cellulose esters, polyethyleneterephthalate or on a nontransparent reflecting material such as paperor an opaque cellulose ester. It is often desirable first to coat asubbing layer to the support, this practice of subbing being well knownin the art.

The coating procedure may comprise any of the standard proceduresemployed in industry, such as roller coating, brush coating,dip-coating, spraying, using a doctor blade or an air blade to controlthe thickness and distribution of the coating composition.

The following example illustrates the present invention.

EXAMPLE A series of three aqueous gelatin solutions comprising per kg 50g of gelatin were prepared.

To each of these gelatin compositions a certain amount of coating aidwas added as listed in the table below.

Coating aid used per kg gelatin solution sq.m.

Repellency spots per 15 ml of a 12 aqueous solution of saponine 8 10 mlof a aqueous solution of compound I l ml of a 5 aqueous solution ofcompound I 2 We claim:

1. A coating composition comprising a hydrophilic colloid and at leastone surface active compound corresponding to the formula:

C-(CHz-) SO3M Bails.

wherein: M stands for hydrogen, an alkali metal atom, ammonium ororganic ammonium, n stands for 0 or 1, R stands for hydrogen or when n 1may be alkyl, and each of R and R stands for a straight-chain orbranched-chain alkyl group or together represent the atoms necessary toclose an alicyclic ring structure, and the moiety 2)rt l i contains from10 to carbon atoms.

2. A photographic element comprising a support and one or morewater-permeable collaid layers including light-sensitive silver halideemulsion layers wherein one or more of said layers comprise a compoundcorresponding to the formulaf wherein: M stands for hydrogen, an alkalimetal atom, ammonium or organic ammonium, n stands for 0 or 1, R standsfor hydrogen or when n =1 may be alkyl, and each of R and R stands for astraight-chain or branched-chain alkyl group or together represent theatoms necessary to close an alicyclic ring structure, and the moietycontains from 10 to 20 carbon atoms.

3. A coating composition according to claim 1,

V wherein the said compound is present in an amount of from 0.01 to 5percent by weight based on the weight of dry colloid.

4. A coating composition according to claim 1, wherein the hydrophiliccolloid is gelatin.

5. A photographic element according to claim 2, wherein the saidcompound is present in the said layer in an amount of from 0.01 to 5percent by weight based on the weight of dry colloid in the said layer.

6. A photographic element according to claim 5, wherein the said colloidis gelatin.

7. A photographic element according to claim 2, wherein the said colloidlayer'comprising the said compound is a light-sensitive silver halideemulsion layer.

8. A photographic element according to claim 2, wherein the said colloidlayer comprising the said compound is a protective hydrophilic colloidlayer coated over a silver halide emulsion layer.

9. The coating composition of claim 1 wherein the surface activecompound is isooctadecyl sulfonate.

10. The coating composition of claim 1 wherein the Surface activecompound is isohexadecyl sulfonate.

11. The photographic element of claim 2 wherein said compound isosooctadecyl sulfonate.

12. The photographic element of claim 2 wherein said compound isisohexadecyl sulfonate.

2. A photographic element comprising a support and one or morewater-permeable colloid layers including light-sensitive silver halideemulsion layers wherein one or more of said layers comprise a compoundcorresponding to the formula:
 3. A coating composition according toclaim 1, wherein the said compound is present in an amount of from 0.01to 5 percent by weight based on the weight of dry colloid.
 4. A coatingcomposition according to claim 1, wherein the hydrophilic colloid isgelatin.
 5. A photographic element according to claim 2, wherein thesaid compound is present in the said layer in an amount of from 0.01 to5 percent by weight based on the weight of dry colloid in the saidlayer.
 6. A photographic element according to claim 5, wherein the saidcolloid is gelatin.
 7. A photographic element according to claim 2,wherein the said colloid layer comprising the said compound is alight-sensitive silver halide emulsion layer.
 8. A photographic elementaccording to claim 2, wherein the said colloid layer comprising the saidcompound is a protective hydrophilic colloid layer coated over a silverhalide emulsion layer.
 9. The coating composition of claim 1 wherein thesurface active compound is isooctadecyl sulfonate.
 10. The coatingcomposition of claim 1 wherein the surface active compound isisohexadecyl sulfonate.
 11. The photographic element of claim 2 whereinsaid compound is osooctadecyl sulfonate.
 12. The photographic element ofclaim 2 wherein said compound is isohexadecyl sulfonate.